[sane-devel] sanner still jogs - more buffering ?

[Olaf Meeuwissen]

Pete Lancashire <pete at petelancashire.com> writes:

> Looking for suggestions on how to get my scanner to scan a full page
> at full speed and
> not have to 'jog' 3 or 4 times.
>
> Scanner is a Epson GT-30000. In slow speed it works, in full speed it "jogs"
>
> System: HP DL580G3
>      4 ea dual core 3GHz Zeon cpus
>
>      Adaptec 29320 PCI-X 133 on a bus not shared with any other PCI device
>      LSI ?? 320 PCI-X 133 on a bus not shared with any other PCI Device
>
> Fedora15
>
>      8 GB  RAM DISK created from the above RAM
>
>     Latest packages from Epkowa
>
>     dll.conf consists of only epkowa
>
> Scanner Epson GT-30000 Connected VIA SCSI 68 pin (wide)
> Scanner ONLY RUNs at SCSI-2, 20 MB/s (40 MB/s transfer since wide I AM
> ASSUMING THIS, waiting to hear back from Epson)
>     NOTE: Just confirmed from Epson, their online documentation lies
> in that it says SCSI-3
> A full scan, 600 DPI color at full speed should take 8.058 Seconds and
> create a file approx 204 MBytes
> 0.79 mS per line, 10,200 lines
> 7,020 x 10,200 or 71,604.000 pixels
> 24 bits per pixels
>
> The key is 204.86 Megabytes in 8.058 Seconds which is 25.43 Megabytes
> per second.
>
> tests were done sending the output of scanimage to /dev/null.
>
> time scanimage --color-correction='No Correction' --mode=Color
> --resolution=600 --speed=yes > /dev/null
>
> some of the things I've done and tried
>
> installed the latest epkowa packages
>
> changed dll.conf to just epkowa (deleted everything other then epson2
> which is commented out)
>
> increased /proc/scsi/sg/def_reserved_size to 1 Meg
> changed .../allow_dio to 1 (enable)
> increased SANE_SG_BUFFERSIZE to 1 Meg (and even higher)

Pete, could you provide the scsi-debug.log created by:

  SANE_DEBUG_SANEI_SCSI=16 scanimage > /dev/null 2> scsi-debug.log

so I can have a look at what's going on?  I had a look at the code and
suspect the epkowa backend inadvertently uses an internal max buffer
size of 32k :-( This could lead to sub-optimal image transfer requests
to the scanner.

> I've also downloaded the lastest sane, built it with gcc -march / tune
> = native, same resulits
>
> =========================================
> Increasing the buffers to their max/1MB does help
>
>>From the sources can I increase the buffer(s) in sane ? I have 16 GB
> or RAM to play with
>
> Can I 'sniff' the SCSI bus to see if it is sane telling the scanner to
> wait or is it the scanner it self ?
>
> Other suggestions ?

Hope this helps,
-- 
Olaf Meeuwissen, LPIC-2           FLOSS Engineer -- AVASYS CORPORATION
FSF Associate Member #1962               Help support software freedom
                 http://www.fsf.org/jf?referrer=1962